The present invention relates to control over heating, ventilation and air-conditioning systems in a vehicle, and more particularly to control over heating, ventilation and air-conditioning systems in a vehicle having multiple environmental zones.
Many vehicles have two or more independent environmental zones serviced by separate heating, ventilation, and air-conditioning (HVAC) systems, each zone capable of possessing separate settings for temperature, air intake, ventilation and the like. One common example of a multizoned vehicle is a commercial freight truck that typically includes a cab zone containing the front seat and vehicle driving controls, and a sleeper zone where the driver and/or passenger can rest. The HVAC system for each zone is essentially separate with separately located HVAC controls. In some circumstances, limited on/off control of the sleeper zone HVAC system is available from the cab zone, and vice versa. However, in such circumstances, the only method for regulating the temperature in a zone other than the one in which the user is currently located is to cycle the HVAC system for the other zone on and off. This method is impractical and inefficient, especially in a vehicle. Accurate adjustment of the temperature of the sleeper zone, for example, requires the driver to stop the truck and physically move to the sleeper zone to change the temperature control.
Environmental zones with separate HVAC controls can also create undesirable drafts between the zones. Under cold climate conditions, for example, the cab zone HVAC system may push heated cab air up into an unheated sleeper zone. The warm air entering the upper area of the sleeper zone displaces the cool air toward the floor area of the sleeper zone, which then circulates back into the lower cab zone, causing a draft and discomfort to the operator""s legs. If the sleeper zone HVAC system is turned on in order to heat the sleeper zone and counter the draft, the sleeper zone may eventually become warmer than the cab zone and cause drafts of warm air from the sleeper zone to raise the overall cabin temperature. Eventually, it becomes necessary for the driver to turn off the sleeper zone HVAC system in order to cool the cab zone.
The reverse may occur under warm climate conditions. The cab zone HVAC system may push cool air toward the bottom of a hot sleeper zone, displacing the warm air up and back to the cab zone onto the operator""s head. Again, the operator can activate the sleeper zone HVAC system to cool the sleeper zone and counter the draft. The sleeper zone may eventually become cooler than the cab zone and cause the overall cabin temperature to go below the desired temperature setting. Again, it eventually becomes necessary for the driver to turn off the sleeper zone HVAC system in order to warm the cab.
A need therefore exists for an HVAC control system in a multizoned vehicle that provides an operator full control over the environment in any zone of the vehicle from any other zone. The present invention is directed to satisfying this need and other shortcomings in the prior art.
The present invention provides an HVAC control system for a multizoned vehicle that allows a user to control the HVAC system of any zone from any other zone. The HVAC system that regulates the environment in a particular zone is preferably controlled by an electronic control unit associated with the zone. The electronic control unit in each zone communicates with a corresponding control head that provides an interface between the user and the HVAC system of the zone. In accordance with the present invention, the control elements of a particular zone (i.e., the electronic control unit and control head) communicate with corresponding control elements (i.e., electronic control units or control heads) of the other zones by way of a datalink implemented in the vehicle. The invention may advantageously use an existing multiplexed data communication bus in the vehicle as the datalink.
According to one aspect of the invention, the electronic control unit and/or control head of a zone may assume a xe2x80x9cmasterxe2x80x9d or xe2x80x9cslavexe2x80x9d status. Each control head typically includes mechanisms for controlling temperature, airflow and other relevant settings. By assigning master status to the control elements of the zone in which the user is physically located, the user can control the settings for each HVAC system associated with other zones in the vehicle. A zone selection control is used to determine which zone""s HVAC system is affected by the inputs to the control head.
According to another aspect of the invention, the control head may be composed of a control panel that includes automatic controls or manual controls for controlling the climate in a zone. The control panel may also include a combination of automatic and manual controls.